This invention relates to a fuel injection system and a method of injecting fuel in an internal combustion engine so as to provide better and more stable idle operation.
The advantages of direct cylinder injection are well known. It is also understood that direct cylinder fuel injection can be particularly useful in two cycle crankcase compression internal combustion engines as a method for controlling exhaust emissions and running characteristics. That is, direct cylinder injection can, under some circumstances, improve misfiring, uneven combustion and the emission of hydrocarbons. Although direct cylinder fuel injection can improve these characteristics, the direct cylinder injection systems and methods previously proposed have not been completely satisfactory in insuring good and stable idle speed.
One reason for this is that the engine speed is normally changed by adjusting the duration of fuel injection. It is difficult, however, to maintain the desired idle speed by adjusting primarily the fuel injection duration. That is, if the system is capable of maintaining good accuracy and reliability of idle operation, it will be difficult to provide the adequate amount of fuel through the entire range required for the injection system. As a result, there is normally a sacrifice in idle speed stability with injection systems of this type.
It is, therefore, a principal object of this invention to provide an improved fuel injection system and method for an engine and particularly for maintaining the idle speed of the engine constant.
It is a further object of this invention to provide an improved and simplified fuel and air injection system for an engine that will maintain good and stable idle speed under varying conditions.